Author Topic: 1909 Mercedes Aero Engine  (Read 45597 times)

Offline Lars

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Re: 1909 Mercedes Aero Engine
« Reply #210 on: June 17, 2019, 10:26:05 PM »
Steve,
Looking good. I had some broken drills and some attempts before sucessfully drilling the 'tube'

Man, it does suck to be me right now but I wanted to give you a heads up. I have been struggling with the compression on cylinder 3,4 for some reason for a while. Also, the engine ran ~ fine until it got warm, then it only ran on two cylinders 1,2 and never wanted to rev. I was sure it was leakage in the valves, so I relapped and even redid one valve and didn't think too much of the cold vs warm issue.
 
Today after becoming pretty sure I had a seal on the valves, I did a more thorough leakge test using water and blowing air into the intake and exhaust looking for air bubbles in the valves I realized they were just fine, but I had bubbles from what could only be a crack/porosity in the casting  :(

Looking into more detail, sure enough, there are some small small hairline defects that appearantly goes from the cylinder, into the waterjackets and are also connected into the intake bores. They probably open up enough during heat-up to a level where the compression goes completely away.

Hard to see on the picture, but before assembly I would just to a leak test to make sure your good to go. I have assembled/reassembled my engine probably 6 times now before I realized this issue

P.S, if anyone have a magic trick that somehow could solve this topic or have a casting that they think they will not use, I would be very much interested. But I assume my cyl 3,4 casting is scrap






Offline 90LX_Notch

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Re: 1909 Mercedes Aero Engine
« Reply #211 on: June 17, 2019, 11:03:57 PM »
Steve-

I have been following along for sometime and just noticed that I never commented.  Nice work and I like the tubing bender.

-Bob
Proud Member of MEM

My Engine Videos on YouTube-
http://www.youtube.com/user/Notch90usa/videos

Offline bent

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Re: 1909 Mercedes Aero Engine
« Reply #212 on: June 18, 2019, 06:54:41 PM »
Given the amount of effort you've put in, I would try and seal the cracks.  Loctite in wicking grade, or similar (acrylic based) sealers, might do it and would be where I would start.  Paint the surfaces and then pull a vacuum on it from the backside if possible.  If not possible to do that, then dunk the whole part in resin and pull a vacuum (shop vac vacuum is usually enough, and cycling the vacuum on/off helps the sealant wicking by pulling bubbles out of the cracks).  The vacuum vessel could be a plastic bag if need be.  If the loctite acrylic resins fail to stop the leak, you can bake at around 400~500F to bake them out.  Sodium silicate is another method to try, paint it on and let it soak in (vacuum here can help too), then heat it up to about 250 F and let it foam out and seal.  We have vacuum impregnation done on our castings at work all the time, and have a local shop do the work in batches for us...might see if you can find one nearby and piggy back your parts in a production run.  The acrylic resins work fine at 250F and 10 bar pressure for us.

Offline Lars

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Re: 1909 Mercedes Aero Engine
« Reply #213 on: June 19, 2019, 08:42:55 AM »
Bent,

Thank you so much for these great tips,  I sincerecly appreciate your reply. I shall definetily try and see if I can get them to seal using a wicking loctite first and then go from there.
Yes, I certaintly had a bad moment summarizing all hours that went into the part so anything I can try to save it I will try.

-Steve, I apologize for diverting the thread with this topic, I shall start my own thread on my efforts to get my engine to run properly.

Thanks!
Lars

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #214 on: June 19, 2019, 10:21:52 AM »
Hi Lars.

What a disappointment. A difficult one to find too. Do you think it is original porosity or has it happened later? I like your suggestions, Bent. All is not yet lost.

I have not yet tried the compression on mine as I haven't fitted the valves but the final assembly is getting closer. Don't worry about hijacking the thread. It is nice if all of the issues are in the same place so that anyone else doing one of these can find them all!

In the mean time, I have fitted the carburettor body to the inlet manifold tubes using Loctite. The bolt holes will need easing slightly but it is beginning to look nice.





Good luck Lars!

Steve

Online sco

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Re: 1909 Mercedes Aero Engine
« Reply #215 on: June 19, 2019, 10:55:25 AM »
Certainly does look nice!  Making my palms itch to start mine too!

Simon.
Ars longa, vita brevis.

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #216 on: June 19, 2019, 01:21:59 PM »
It is beginning to sound as if therre are quite a few sets of castings out there but not many people have made one. I can't criticise as my castings were on the shelf for two years before I started cutting metal!

 Steve  :)

Offline Jo

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Re: 1909 Mercedes Aero Engine
« Reply #217 on: June 19, 2019, 01:53:49 PM »
It is beginning to sound as if therre are quite a few sets of castings out there but not many people have made one. I can't criticise as my castings were on the shelf for two years before I started cutting metal!

Only two years worth of casting aging  :facepalm:

Steve - you must have brought yours just after we brought ours at the Midlands show in 2016. We are still aging ours ;)

Jo
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Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #218 on: June 19, 2019, 09:30:24 PM »
Actually, I have just realised that I bought the castings in 2012. Time flies.....

Lars.

I have just been looking at the carburettor again and have at last fathomed how it works. Did you set yours up so that it richens the mixture as you open the throttle or so that it weakens the mixture? I am not quite sure which is the correct way to do it!

Cheers!

Steve  :) 

Offline Lars

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Re: 1909 Mercedes Aero Engine
« Reply #219 on: June 19, 2019, 10:07:34 PM »
Hi Steve

Engine looks great. I like your bends on the carb manifold tubes, for me it took a while to get the carb aligned horizontally with the engine. Yours look spot on.

haha, yes, It took me a while to figure out the carb function as well. Now I am not sure I did things 100% right, but at least the engine fired well on 2 out of 4 cylinders with my carb settings so this is how I set it up:

I have the throttle 'needle' (as you know it is a flat needle going into the hollow tube) adjusted so that when the throttle is at ~idle (1/8 opening maybe?) I can barely see the opening in the small atomizer hole in the tube, hence almost blocket by the 'needle' . Then as the throttle is advanced the hole is almost 100% clear of the needle att fulll throttle.
(For adjustment I turn the fuel inlet assembly so that the hole in the tube is visible from the air inlet side of the carb)
However, honestly through the effort so far of getting a running engine I found this needle to make much less difference than the fuel inlet needle.

For the fuel inlet needle I had approx a turn and a half, then the engine would fire well idle-->half throttle, but would require me to open up the valve half a turn more to get it to fire on 3/4 to full throttle

But as you know, I have not been able to get my engine to run very well as I have the leakage issue so I am sure I have much more adjustment to do when the engine is more healthy.

In my endeavour to save my casting and with the great advice from Bent, I today took the Loctite 209 290 which is the lowest viscosity one I could think of and tried to vacuum seal the casting. (Filled the top part with loctite and pulled air out of the waterjacket inlet, then cleaning leftovers and left to set). I am certaintly holding my thumb for this to work. I will do another leak test tomorrow when it has had a chance to cure. 

Sounds great if you allow to have the dialouge on the mercedes engine in your thread

Thanks!
Lars
« Last Edit: June 19, 2019, 10:13:49 PM by Lars »

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #220 on: June 23, 2019, 10:11:56 AM »
Ok Lars. You have set the throttle to lean the mixture at idle and richen it as you advance the throttle. As it is a barrel throttle, it can be opened by turning it either way. Turning it clockwise winds the flat ended mixture needle in, reducing the jet size so you must be opening the throttle by turning it anti-clockwise. This thing is a puzzle. I am looking forward to playing with it!

In the meantime, I have made up a dummy float chamber.





Now, the throttle lever. This isn't drawn but appears to screw onto the end of the throttle barrel. I roughed out a shape from a piece of 1/8" aluminium.



Now spot the challenge! I couldn't screw it right on as it fouls the manifold. In the end, my cure for that was to drill the thread out and clamp onto the outside of the thread. I may have to turn up a new barral with just a plain shank for the lever to grip.





Quite a lot of time with a needle file but I am pleased with the result.



Finished and ready to fit!



The last time I spoke to Adrian, who supplies the castings, he said that he was looking at getting the valve rockers investment cast and would I like a set? Well, that would save a huge amount of repetetive work so yes please! Here they are, beautifully presented. Finishing them off is my next task.





I have ordered some Delrin for the distributor so I am almost at the point of final assembly. I can't see that being a quick job though!

Steve  :)

Offline steamer

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Re: 1909 Mercedes Aero Engine
« Reply #221 on: June 23, 2019, 02:50:26 PM »
That's looking a treat Steve.   Those castings look amazing as well!

Dave
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Damned ijjit!

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #222 on: June 24, 2019, 07:29:21 PM »
Thanks Dave. Yes, I think they look good too. Devils to hold though!







Time to start on the final assembly, finishing bits off properly. I shall make up the push rods on assembly. Distributor remains to be done and then it will be the moment of truth!

Steve  :)

Offline bent

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Re: 1909 Mercedes Aero Engine
« Reply #223 on: June 25, 2019, 06:13:36 PM »
Wow, looking good Steve!

Offline Lars

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Re: 1909 Mercedes Aero Engine
« Reply #224 on: July 11, 2019, 07:58:28 AM »
Steve,

Oh man does those rocker arm castings look great !!!  I wish so that I would have had one of those sets !

I silver-soldered my rocker arms out of 4 pieces each to get a thin good looking part and it took a loong time just due to the small size, holding and getting the welder to heat where I needed witouth unsoldering other pieces etc.... and at the end I have 8 individual looking ones (well if you look close at least you can see I was unable to get them to look identical)

Nice!

Lars

 

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